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• <br /> of Ethers and Alcohols in Gasoline by Gas Chromatography, SOP NO MLD 1151, <br /> including TBA, with a method reporting limit of 0 1% mass, or 1000 rng-TBA/kg- <br /> gasoline The CARB analysis method is similar to ASTM D4815 and ASTM D5599 <br /> methods All of the estimated TBA levels in MtBE-oxygenated gasoline shown in the <br /> above table would not have been detected if analyzed at the CARB method detection <br /> limit <br /> Equilibrium partitioning factors between gasoline and water for a number of oxygenates, <br /> including TBA, have been measured by Shell in a series of batch gasoline-water <br /> partitioning tests Measured partitioning values (Kg.,,line_water) for TBA fall in the range of <br /> 0 05 to 0 26 (mg/L-gas oline)/(mg/L-water), with a nominal geometric mean of 0 11 <br /> (mg/L-gasoline)/(mg/L-water) This range of partitioning factors is in reasonable <br /> agreement with factors estimated from physical properties Variation in the measured <br /> partitioning factor is due a number of influences, including experimental variability, tests <br /> of multiple gasoline compositions, and tests of multiple concentration ranges for mixtures <br /> of oxygenates <br /> An estimate of the concentration of TBA in water in contact with gasoline is given by <br /> _ CTBA—gasohne !"gasoline <br /> CTBA—xater <br /> Kgasohne—water <br /> Using nominal values of <br /> pgasohne — 0 91 (kg-gasoline/L-gasoline), density of gasoline <br /> Kgasohne-waler= 0 11 (mg-TBA/L-gasoline)/(mg-TBA/L-water), partitioning factor <br /> and <br /> CTBA—water (mg-TBA/L-water), calculated <br /> CTBA—gmolme (mg-TBA/kg-gasoline), initial estimate <br /> yields a range of calculated TBA concentrations in water <br /> For estimating concentrations of MTBE in water in contact with unweathered gasoline, <br /> we use Raoult's law partitioning �T�� <br /> 6 kg 1y1 r�gasohne r. <br /> CMtBE water — CMrBE—gasohne 1 ] <br /> mg MWMIBE <br /> with <br /> MWgasahne — g0 1 g/g-mole nominal average molecular weight of gasoline <br /> MWMIBE= 88 15 g/g-mole molecular weight of MTBE <br /> S =42000 mg/L-water pure chemical aqueous solubility limit of MTBE and <br /> CMTBE—waler (mg-MTBE/L-water), calculated <br /> CMTBE_gasohne (mg-MTBE/kg-gasoline), initial estimate <br /> 10 <br />